Jonny Sexton has given Ireland's coach Declan Kidney the sort of selection headache he always hoped for. On one hand, he has the tried and tested figure of Ronan O'Gara, the British Lion with 95 caps to his name. On the other, the new pretender at No10 in Jonny Sexton, who announced his arrival on the international stage with a man of the match performance here on Saturday night.

With the world champion Springboks to come to Croke Park on Saturday, the Ireland coach now has some thinking to do. The odds are that he will start O'Gara as Ireland try to stretch their unbeaten sequence to 11 games. Now, however, he has on the bench a player who can come on and change the game – a luxury denied his predecessor, Eddie O'Sullivan.

Seven successful kicks from seven attempts was the top statistic from Sexton's night against a Fiji side improved from the previous week, but he did more besides – starting with a clean break from his own 22 in the opening minutes of a game that did not become a one-way affair until the final quarter, when Brian O'Driscoll sickened the tourists with a 50-metre intercept try.

Afterwards Kidney and Sexton competed with each other in understatement. Indeed the coach brought the house down with his reply to how the debutant had fared. "He did OK ," Kidney said. "I heard people saying last year that if Ronan [O'Gara] got injured we were in big trouble, but I always thought that wasn't fair on Jonny. He didn't do anything today that I haven't seen him do over the last year or two. It was a special day for him but he's mature enough to know that he had good service on the inside and good support on the outside and that helps."

The only downside for Kidney was the loss of Denis Leamy with an ankle-ligament injury likely to keep him out of the South Africa game. Ireland led 13-6 at halftime and pulled away in the final quarter with Keith Earls adding to his first half try, and Shane Horgan and Rob Kearney touching down.